By Lindsey Konkel
The Daily Climate, March 25, 2014
Deep red sunsets offer more than just a stunning backdrop for Old Masters’ paintings: They can tell how dirty the air was when the painter picked up the brush.
The degree of red in the skies depicted in historic paintings offers a proxy for pollution levels in the Earth’s past atmosphere, according to a study published Tuesday. What’s more, artists’ sunsets have gradually gotten redder over the past 150 years, likely reflecting increased manmade pollution.